Production of unsaturated carbonyl compounds



United States Patent PRODUCTION OF UNSATURATED CARBONYL COMPOUNDS Harry A. Cheney, Berkeley, and Irwin L. Breier, Lafayette, Calif., assignors to Shell Development Company, New York, N.Y., a corporation of Delaware No Drawing. Application March 25, 1957 Serial No. 647,966

Claims. (Cl. 260-604) enabling the more efficient production of acrolein by the =(controlled catalytic oxidation of normally gaseous hydrocarbons comprising propylene.

This is a continuation-in-part of application Serial No. 445,484, filed July 23, 1954, now abandoned.

It has been disclosed heretofore that alpha,beta-unsaturated aliphatic aldehydes and ketones, valuables as starting and intermediate materials in the production of chemical derivatives therefrom, are obtained by the controlled partial oxidation of olefinic hydrocarbons. In such a process the obtaining of any substantial amount of the desired alpha,beta-unsaturated carbonylic compounds is dependent upon the use of carefully controlled specific operating conditions employing specific catalysts. In U.S. Patent 2,486,842 there is disclosed and claimed a process wherein olefinic hydrocarbons having at least three carbon atoms to the molecule are contacted with cuprous oxide in the presence of oxygen under conditions at which a substantial amount of the olefin is oxidized to unsaturated carbonylic compounds containing the same number of carbon atoms per molecule as the olefin. Even in the presence of cuprous oxide catalyst, shown to be unique in its ability to convert olefinic hydrocarbons to alpha, beta-unsaturated carbonylic compounds, there are formed, in addition to the desired alpha,beta-unsaturated aliphatic aldehydes and ketones, substantial amounts of by-products comprising, for example, more completely oxygenated derivatives including organic acids and oxides of carbon as well as substantial amounts of hydrocarbon by-products. The relative proportions of these undesired byproducts produced will vary considerably in accordance with materials charged to the process and specific operating conditions employed therein.

Methods have been disclosed heretofore directed to suppressing the formation of undesired by-products in such a process for the production of the desired alpha, beta-unsaturated carbonylic compounds by partial oxidation of olefins in the presence of cuprous oxide. In U.S. Patent 2,486,842 it is disclosed and claimed that the inclusion of a chlorine compound in the charge to the process will aid materially, in increasing the yield of the desired alpha,beta-unsaturated carbonylic product. It has been believed heretofore that such effect upon the cuprous oxide catalyst in the controlled oxidation of olefins was limited solely to the chlorine compounds and U.S. 2,486,842 states that it does not extend to other halogen compounds. It has now been found that far superior results in terms of promotional effect and by-product suppression in the cuprous oxide-catalyzed controlled oxida- I 2,879,300 Patented Mar. 24, 1959 tion of olefins are obtained by the additionof elementary iodine to the charge, provided the iodine, in uncombined form, is added in exceedingly small quantities within a well-defined range. The use of chlorine compounds in large scale operations of the controlled olefin oxidation often results in an inordinate increase in the rate of carbonaceous deposit formation upon catalyst and in equipment. Quite surprisingly, the use of iodine as promoter is substantially entirely free of this highly disadvantageous effect thereby enabling the operation to proceed for considerably prolonged periods of time without substantial deterioration of catalyst or diminution of catalyst activity.

In accordance with the process of the invention unsaturated carbonylic compounds containing an olefinic linkage between two carbon atoms of aliphatic character, one of which is linked directly to the carbon atom of the carbonyl group, are obtained with improved efficiency by contacting an olefinic hydrocarbon having at least three carbon atoms, in admixture with oxygen, with a cuprous oxide-containing catalyst at an elevated temperature in the presence of added elementary iodine. In accordance with the process of the invention alpha,beta-unsaturated carbonylic compounds comprising acrolein are obtained with improved efliciency by contacting olefinic hydrocarbons comprising propylene, in admixture with oxygen, with a cuprous oxide catalyst at an elevated temperature in the range of from about 200 to about 600 C. in the presence of added uncombined iodine.

The process of the present invention is applicable generally to the conversion of olefins of three or more carbon atoms to unsaturated carbonylic compounds of the class consisting of the unsaturated aldehydes and the unsaturated ketones by oxidation in the presence of a solid cu prous oxide catalyst. By the term olefin as used herein and in the appended claims is meant the open-chain as well as cyclic olefins. Among the many olefinic compounds which are adapted for use as starting materials, the following may be mentioned: propylene, butene-l, butene- 2, isobutylene, diisobutylene, pentene-l, pentene-Z, 3- methyl-butene-l, 2-methyl-butene-2, hexene-l, hexene-Z, 4-methyl-pentene-1, 3,3-dimethyl-butene-1, 4-methylpentene-2, octene-l, cyclopentene, cyclohexene, 3-methyl-cyclohexene, etc. These compounds and their various homologs may be substituted in the nucleus and/or in the substituents in various degrees by straight chain alicyclic and/ or heterocyclic radicals. The olefins may be treated individually or as mixtures with each other, or with the corresponding parafiins or other saturated organic compounds. When treated in mixtures, for example, with the corresponding paraffin, the parafiin may remain substantially, if not wholly, unaffected. In other words, bythe present process it is possible to selectively incompletely oxidize olefins; saturated compounds, if present, acting merely as diluents.

Oxygen employed in converting olefins of the aboveidentified class to the unsaturated carbonylic compounds, in accordance with the invention, may be obtained from any suitable source. The oxygen may be employed as such in relatively pure state, or in the form of an oxygen-containing gas, such as, for example, air. The ratio of oxygen to paraffin charged to the process may vary considerably within the scope of the invention. In general the olefin is added in substantial excess over the stoichiometrical amount; the maximum amount of oxygen tolerated being defined by the explosive limit under the specific operating conditions employed. Molar ratios of olefin to oxygen between about 1:1 and 8:1 generally give satisfactory results. Higher ratios of olefins to oxygen in the range of up to, for example, about 30:'l are often advantageously employed.

Essential to the attainment of the controlled catalytic partial olefin oxidation is the use of copper as catalyst in the form of cuprous oxide. The cuprous oxide employed in the execution of the process of the invention preferably is supported on or mixed with a suitable carrier material, such as silica gel, silicon carbide porous aggregates, pumice, aluminous materials such as bauxite, activated aluminas, also activated carbon, silica-alumina, magnesis, and the like. impregnation of the oxide on the carrier may be carried out, for example, by treating the degassed carrier with a concentrated solution of cupric nitrate or chloride or with an ammonium compound comprising copper, as copper ammonium nitrate. The nitrate and ammonium compounds may be decomposed to cuprous oxide by first heating the dried carrier between about 250 C. and 400 C. in a slow stream of air and then reducing the cupric oxide thus formed to cuprous oxide with hydrogen or other suitable reducing agent. Substantially the same procedure is followed in the preparation of the catalyst from the chloride except that repeated oxidation and reduction may be necessary. Cupric oxide is generally ineffective when applied in lieu of cuprous oxide in the execution of the process.

A particularly suitable catalyst for use in the process of the invention comprises one consisting essentially of cuprous oxide in admixture with an aluminous material, such as, for example, Aloxite. When employing a catalyst of solid support material in addition to the cuprous oxide the copper content of the catalyst may vary considerably within the scope of the invention. Thus, the copper content of the total catalyst including support or diluent material may range, for example, from about 0.5% to about 25%, and preferably from about 5 to about 15% by Weight calculated as metallic copper. Higher or lower concentrations of copper may, however, be employed within the scope of the invention.

Normally gaseous materials, or materials which are vaporous under the conditions of execution of the controlled oxidation and which are relatively inert, may be employed as diluents. Such diluent materials, comprise, for example, nitrogen, steam, normally gaseous paraffins, etc.

In effecting the process of the present invention, considerable latitude is permissible in the reaction temperature. However, the reaction temperature, i.e., the temperature of the catalyst, preferably is maintained in the range of from about 200 C. to about 450 C. Catalyst temperatures as high as about 600 C. have at times been found permissible. The temperature used depends primarily upon the catalyst, the particular olefin being treated, and the correlated conditions of the rate of throughput or contact time, and the ratio of olefin to oxygen. Apparent contact times of from about 0.1 sec. to about see. generally are satisfactory. The apparent contact time may be defined as the length of time in sec- 'onds a unit volume of gas measured under the conditions of reaction is in contact with a unit apparent volume of the catalyst. It may be calculated, for example, from the apparent volume of the catalyst bed, the average temperature of the catalyst, the pressure (if different from atmospheric), and the flow rates of the several components of the reaction mixture. Aid in temperature control is obtained, for example, by diluting the reaction mixture with steam, by operating with an excess of olefin, by using a carrier or supporting material which is a good heat conductor, etc. The cuprous oxide, alone or supported on a suitable carrier material, may be used in finely divided state, as a dust, a fluidized form, dense phase suspended form, and under conditions facilitating dissipating heat of reaction. The reaction may be conducted at any pressure commensurate with the temperature at which it is desired to operate, but usually the reaction is carried out at approximately atmospheric pressure to avoid the possibility of encountering conditions leading to explosion or autoignition of the reaction mixture.

Pressures in the range of from atmospheric to about 1000 pounds per square inch gauge, and preferably from about atmospheric to about 250 p.s.i.g. are satisfactory.

Essential to the attainment of the objects of the invention is the use of the cuprous oxide catalyst in the presence of added elementary iodine. The elementary iodine is effective only when present in only exceedingly small amounts. Its addition in uncombined form in amounts ranging, for example, from about 0.1 to about 1000 molecules of iodine per million molecules of olefins, preferably from about 1 to about molecules of iodine per million molecules of olefins, and still more preferably from about 1 to about 10 molecules of iodine per million molecules of olefins, will generally be found satisfactory. The use of higher or lower amounts of iodine is, however, comprised within the scope of the invention. A particular advantage of the invention resides in the ability to obtain the objects thereof with the use of only small amounts of iodine within the defined suitable range. The use of larger amounts generally does not result in any substantial promotional effect. Optimum results are obtained with the use of the promoter within the above-defined range. Because the efiect of the uncombined iodine is retained for a relatively prolonged period of time it need not be added continuously throughout the operation. The promoter may, therefore, be added continuously, periodically, or intermittently, as desired within the scope of the invention. The cuprous oxide catalyst may be preconditioned by pretreatment with the promoter. Such pretreatment may comprise, for example, contact with elementary iodine at an elevated temperature, for example, a temperature approximating, or somewhat exceeding, the reaction temperature.

The invention is not limited to the use of any specific method for the introduction of the elementary iodine into the reaction zone. It is to be stressed, however, that in view of the exceedingly small amount of the promoter employed, care must be taken to see that the promoter does actually arrive in the catalyst bed and is not lost in any part of the system preceding the reaction zone. The passage of make-up iodine through extensive equipment, such as preheaters, distributors, mixers, etc., outside the reaction zone will often result in failure to obtain the desired promotional elfect. This is particularly so when the wall surface of such equipment in contact with the promoter-carrying stream is capable of reacting with, occluding, or adsorbing, substantial amounts of the iodine under the conditions prevailing therein.

The elementary iodine may be introduced into the reactor system, for example, by direct addition to the olefin charge, to the oxygen, or to both. It may be introduced directly into the catalyst bed. The iodine may be introduced into the catalyst bed as a solid, for example, in the form of a powder, dust, or smoke; as a solution in a suitable solvent; as a suspension in a suitable liquid, gas, or vapor. A specific method enabling its controlled introduction comprises, for example, the passage of a carrying medium through a pick-up drum containing a supply of elementary iodine, while controlling the temperature and pressure maintained in the drum. The promoter may be maintained in the pick-up drum in solid form, for example, supported upon a suitable inert solid material, or it may be in the form of a solution in a suitable solvent.

Under the above-defined conditions olefinic hydrocarbons are converted to the desired alpha,beta-unsaturated carbonylic compounds with substantially improved efficiency as determined by yield of desired product, product distribution and ease with which optimum operating conditions are maintained. An important advantage inherent in the use of iodine as defined above, is the ability to obtain the substantial improvement in the execution of the reaction with the use of exceedingly small amounts thereof.

A particular advantage of the use of iodine in elementary form as promoter for the cuprous oxide-cat? alyzed controlled olefin oxidation resides in a surprising degree of effectiveness in maintaining the catalyst in clean condition and in prolonging its useful active life. Advantages realized to varied degrees by the use of'promoters, such as chlorine compounds, for example, dichloro-propane, used heretofore, are generally quite limited in duration. Their use in large scale operation often is accompanied by rapid fouling of the catalyst necessitating relatively frequent interruption of operation, costly catalyst replacement and cleaning of equipment. The use of uncombined iodine in accordance with the invention, on the other hand, enables the operation under improved conditions to proceed at inordinately prolonged periods of time in the absence of any substantial catalyst deterioration. I

In the production of acrolein by the cuprous oxidecatalyzed controlled oxidation of propylene the use of a chlorine compound, such as, for example, dichloropropane or the like, as promoter will often result in a cat'- alyst fouling rate of a magnitude necessitating catalyst replacement after continuous operation of about 450 hours. The condition of the fouled catalyst is often such that its removal from the reactors is a difficult and costly operation. When iodine in elementary form is used as the promoter, however, under otherwise identical conditions, no substantial degree of catalyst fouling and consequent catalyst deactivation is generally apparent after an equivalent operating period. The catalyst is then generally in a clean condition easily. removed from equipment. 7

The process is applied broadly, as described above, to the production of alpha,beta-unsaturated carbonylic cornpounds from the corresponding olefins. In accordance with the claimed invention propylene is converted to acrolein, isobutylene to methacrolein, alphaor betabutylene to methyl vinyl ketone, pentene-l or pentene-2 to ethyl vinyl ketone and/or pentene-3-one-2,, Z-methylbutene-2 to methylisopropenyl ketone, cyclopentene to cyclopentanone-2. It is applied with particular advantage to the production of alpha,beta-unsaturated aliphatic aldehydes having three and four carbon atoms to the molecule from the corresponding olefinic hydrocarbons having 3 and 4. carbonvatoms to the molecule; for example, the production of acrolein from' propylene, and methacrolein from isobutylene.

Unsaturated carbonylics are recovered from the total oxidation products by conventional means comprising, for example, one or more such steps as quenching by direct contact with a liquid cooling medium such as, for example, a hydrocarbon, water, and the like; scrubbing with water, hydrocarbons, etc.; distillation; extractive distillation; solvent extraction; and the like.

The following examples illustrate practice of the invetion, but are not to be construed as limiting the scope thereof.

ExampleI In an operation identified by the designation run A," propylene was converted to acrolein by controlled incomplete oxidation in the presence of a cuprous oxide catalyst. In the operation a propylene-containing gaseous mixture having essentially the composition M percent Propylene 24 Oxygen 4 Steam 5 8 Nitrogen 14 6 out at a pressure of about 75 p.s.i.g. with a contact time of about 0.2 second. Reaction bed temperatures were controlled, with the aid of electrical heating elements positioned externally about the reactor walls, to obtain maximum production rate of acrolein as determined by percent of oxygen conversion at high acrolein yields.

Under the conditions of run A, executed without promoter addition, reaction mixtures containing substantial amounts of acrolein could not be obtained at oxygen conversions to total oxygenated products above 25%, a figure which is substantially below that indicative of an acrolein production rate commensurate with practical scale operation. When oxygen conversion was permitted to exceed 25% under the conditions of run A by increasing reactor temperature, controlled incomplete oxidation of propylene became impossible, and substantially complete conversion of oxygen charge rapidly took place with the formation of reaction mixtures, consisting predominantly of oxides of carbon and containing no substantial amounts of acrolein.

In each of a series of separate operations identified by the designations run B through F, respectively, the propylene oxidation run of the operation A was repeated under substantially identical conditions, but with the exception that elementary iodine was introduced into the catalyst bed during the operation. Introduction of the iodine into the catalyst bed was obtained by pumping an aqueous solution of the promoter in controlled amount from a storage vessel into the propylene feed line leading into the reactor. The storage vessel presented essentially only a glass surface to the aqueous promoter, and the, storage vessel, as well as the line therefrom leading into the propylene charge line, was maintained substantially. at room temperature.

In a separate operation identified by the designation run G the propylene oxidation as carried out in the operation identified by the designation run A was again repeated under substantially identical conditions, but with the exception that ethane was substituted for the water (steam) component of the feed, and in that iodine was introduced into the reaction bed as a promoter for cuprous oxide catalyst.

I The specific promoter, and the amount thereof employed, as well as the catalyst bed temperature, for each of the separate operations B throughG are set forth in the-following table. The results obtained in terms of percent of oxygen conversion and percent of the reacted propylene which is convertedto acrolein, for eachof the operations runs B through G, respectively, are

also set forth in the followlng table:

Yield of Promoter: Catalyst Oxygen Acroleln on Run Promoter mols/Mil- Bed Conver- Propylene lion mols Temp., sion, Conof feed 0. Percent sumed,

Percent Example I] .C. and a reaction pressure of 85 p.s.i.g. were employed;

and in that 7 moles of chlorine as dichloropropane per million moles of feed to the reactor was added to the charge of run H throughout the operation; and 1.0 mole of iodine per million moles of feed to the reactor was added to the charge of run I. The run H was continued for a period of about 450 hours at the end of which time operation was brought to an unavoidable termination as a consequence of extreme fouling of catalyst and equipment with a carbonaceous deposit and of deactivation of the catalyst as a result of such fouling. The average yield of acrolein obtained in run H" corresponded to 54% based on propylene consumed. The condition of the fouled catalyst made recourse to drilling necessary to elfect its removal from the reactor. In contrast thereto the run I continued efiiciently for a period of about 450 hours at which time the unit was shut down for inspection. No evidence of any substantial degree of fouling of equipment or of catalyst, or any substantial degree of catalyst deactivation due to fouling, were noted. The catalyst was in clean condition and dropped easily out of the reactor without need to resort to drilling. The catalyst was in condition enabling resumption of operation, and equipment was in no need for cleaning before reuse. An average acrolein yield of 65% of propylene consumed was obtained in run I.

It is apparent from the foregoing example that the process of the invention enables the efiicient production of acrolein by the direct, controlled, partial oxidation of propylene at unusually high production rates as condensed by unusually high oxygen conversions coupled with high yields of the desired product.

We claim as our invention:

1. In the process for the production of unsaturated carbonylic compounds containing an olefinic linkage between two carbon atoms of aliphatic character, one of which is linked directly to the carbon atom of the carbonyl group, wherein an olefinic hydrocarbon having at least three carbon atoms to the molecule is subjected to controlled oxidation by contact, in admixture with oxygen, with a solid cuprous oxide catalyst, at a temperature of from about 200 to about 600 C., the improvement which comprises effecting said controlled oxidation in the presence of a promoting amount of elementary iodine.

2. The process in accordance with claim 1 wherein said elementary iodine is added in an amount ranging from about 0.1 to about 1000 molecules of elementary iodine per million molecules of said olefinic hydrocarbon.

3. The process in accordance with claim 1 wherein said elementary iodine is added in an amount ranging from about 1 to about 100 molecules of elementary iodine per million molecules of said olefinic hydrocarbon.

4. The process in accordance with claim 1 wherein said elementary iodine is added in an amount ranging from about 1 to about 10 molecules of elementary iodine per million molecules of said olefinic hydrocarbons.

5. In the process for the production of unsaturated carbonylic compounds having from three to four carbon atoms to the molecule containing an olefinic linkage between two carbon atoms of aliphatic character, one of which is linked directly to the carbon atom of the carbonyl group, wherein an olefinic hydrocarbon having from three to four carbon atoms to the molecule is subjected to controlled oxidation by contact, in admixture with oxygen, with a solid cuprous oxide catalyst, at a temperature of from about 200 to about 600 C., the improvement which comprises effecting said controlled oxidation in the presence of from about 0.1 to about 1000 molecules of elementary iodine per million molecules of said olefinic hydrocarbon.

6. The process in accordance with claim 5 wherein said elementary iodine is added in an amount ranging from about 1 to about molecules of elementary iodine per million molecules of said olefinic hydrocarbon.

7. The process in accordance with claim 5 wherein said elementary iodine is added in an amount ranging from about 1 to about 10 molecules of elementary iodine per million molecules of said olefinic hydrocarbons.

8. In the process for the production of acrolein wherein normally gaseous hydrocarbons comprising propylene are subjected to controlled oxidation by contact, in admixture with oxygen, with a solid cuprous oxide catalyst, ata temperature of from about 200 to about 600 C., the improvement which comprises effecting said controlled oxidation in the presence of from about 0.1 to about 1000 molecules of elementary iodine per million molecules of said normally gaseous hydrocarbons.

9. The process in accordance with claim 8 wherein said elementary iodine is added in an amount ranging from about 1 to about 100 molecules of elementary iodine per million molecules of said normally gaseous hydrocarbons.

10. The process in accordance with claim 8 wherein said elementary iodine is added in an amount ranging from about 1 to about 10 molecules of elementary iodine per million molecules of Said normally gaseous hydrocarbons.

References Cited in the file of this patent UNITED STATES PATENTS 2,486,842 Hearne et al. Nov. 1, 1949 

1. IN THE PROCESS FOR THE PRODUCTION OF UNSATURATED CARBONYLIC COMPOUNDS CONTAINING AN OLEFINIC LINKAGE BETWEEN TWO CARBON ATOMS OF ALIPHATIC CHARACTER, ONE OF WHICH IS LINKED DIRECTLY TO THE CARBON ATOM OF THE CARBONYL GROUP, WHEREIN AN OLEFINIC HYDROCARBON HAVING AT LEAST THREE CARBON ATOMS TO THE MOLECULE IS SUBJECTED TO CONTROLLED OXIDATION BY CONTACT, IN ADMIXTURE WITH OXYGEN, WITH A SOLID CUPROUS OXIDE CATALYST, AT A TEMPERATURE OF FRROM ABOUT 200 TO ABOUT 600*C., THE IMPROVEMENT WHICH COMPRISES EFFECTING SAID CONTROLLED OXIDATION IN THE PRESENCE OF A PROMOTING AMOUNT OF ELEMENTARY IODINE. 